This invention relates to improvements in conveyors and more particularly to devices for preventing conveyor chains from jumping off the drive sprockets around which the chains are trained.
In many industries, particularly the dairy industry, processing plants often employ conveyor lines which feed a palletizing station. At the palletizing station, cases of the bottled dairy products are stacked on pallets for loading aboard trucks. In such conveyors the upper and lower runs are relatively long, and, under normal conditions, these long runs result in a substantial amount of slack in the lower run. The slack runs permit the chains to jump from the sprockets. For example, a sixteen-tooth sprocket may actually effectively utilize only five teeth when a lower run of chain has an average amount of slack. In order to cause more sprocket teeth to engage the chain, the chain may be tightened so as to pull more links of the chain onto the sprocket. This prevents the chain from jumping from the sprocket but since there is then virtually no slack in the lower or return run of the chain, considerable wear takes place in the chain and in the drive mechanism. In due time chain links sometimes must be removed in order to take up more slack. The maintenance problem becomes quite difficult and is really a vicious cycle. The more the chain is tightened, the more teeth of the sprocket are engaged by the chain, and the less likely the chain is to jump over the sprockets; however, with the tighter chain comes more wear and tear on the drive system.